Conventional apparatus, whether stationary or mobile, for packing goods/products using stretch film typically comprise an assembly for unrolling or dispensing the film from a spool and then pre-stretching the same. The assembly feeds the film toward a bundle of goods/products to be wrapped/packed, the bundle usually being supported by a pallet. The spool is unrolled using rubber-covered rollers controlled either by electromagnetic brakes or clutches, or through electronically operated motor reducers. The film then passes over a series of idle conveyance rollers before leaving the assembly and arriving at the bundle to be wrapped.
With a stationary or fixed type apparatus installation, the bundle, which is arranged on an appropriate platform, rotates about its own axis. With mobile apparatus, on the other hand, it is the unrolling and pre-stretching assembly that causes rotation about the bundle, which remains in a fixed position. Rotation of the rubber-covered rollers is often controlled by varying the voltage supply, when electromagnetic brakes or clutches are used, or the number of revolutions in the case of electronically operated motor reducers, holding the stretch film back to a greater or lesser extent, and thus regulating its “stretch” as it is fed. The elastic return then assures stability during the film's wrapping about the bundle.
At the end of the wrapping cycle, the film is cut, either manually by the operator or using an automatic cutter arranged generally downstream of the rollers. When operating the cutter, an initial laceration is made so as to develop transversely into a complete cut by locking the control rollers and then continuing relative rotational movement between the assembly and the bundle. In this manner, the terminal or end flap of film, which is left upon laceration, remains attached to the wrapped bundle or package formed.
Although the above-described arrangements have been found useful, when the film is torn, however, because of the effect of the elastic return of the material, the flap upstream of the cut tends to return into the assembly. As a result, the flap often becomes disengaged from the rollers, necessitating that flap be manually re-positioned on the rollers before resuming operations for the next wrapping cycle. This has been found not only inconvenient and annoying, but also causes substantial loss of time and, therefore, considerable reduction in productivity during wrapping/packing operations.
Furthermore, when the automatic cutter is used, it has been found that development of the cut, and its final position relative to the length of film that has been pulled from the assembly, cannot be accurately controlled. Because a substantial portion of film extends freely downstream of the point where the film is restrained, a tail of film is usually formed that, upon completion of the cut, will dangle from the wrapped/packed bundle in an awkward and tedious fashion. Tail formation also results from the critical angles at which, and the tensions under which, the film often leaves the assembly.